In step-down transmissions known from practice, to engage or disengage gearwheels designed as loose wheels, as a rule shift elements such as synchronizers, claw or frictional elements are actuated by means of shift forks or shift rockers which, in relation to the shaft carrying the loose wheel or a plurality of loose wheels, act upon the shift elements from the outside. In such a case a minimum distance between two loose wheels arranged next to one another, which can be actuated by a common shift element, is determined among other things by the width of a shift sleeve and in addition by the shift path that the shift sleeve has to cover in order to engage the two loose wheels.
Disadvantageously, step-down transmissions in which shift elements are actuated from outside take up a lot of space in the radial direction, such space being of only limited availability especially in automobiles.
To reduce the radial space taken up by a transmission, a change has been made toward actuating shift elements of transmission devices such as double-clutch transmissions, automated variable-speed transmissions or planetary transmissions, from the inside of a shaft carrying loose wheels extend outward, so that from DE 102 06 584 A1, DE 43 25 964 A1 and DE 103 02 502 A1 various systems are known for actuating shift elements extending outward from a shaft by means of a hydraulic, pneumatic, mechanical and/or electromechanical control system.
In mechanical or electromechanical actuating systems known from the prior art for a shift element provided for engaging or disengaging a gearwheel designed as a loose wheel, it is provided for example that the shift element is actuated by a rod passing through the shaft. On the circumferential side of the shaft or the gearset comprising the loose wheel a suitable shift system for producing an H-shift pattern or for electrical actuation is required, but this increases the manufacturing costs and the weight of a transmission device to an undesired extent. Furthermore, the shift system arranged in the circumferential area of a shaft takes up a lot of structural space in the radial direction and also causes friction losses.